Propeller pitch change mechanism



July 21, 1953 J. M. MERGEN ET AL Filed Jan. 29, 1949 PROPELLER PITCH CHANGE MECHANISM 3 Sheets-Sheet l INVENTOR. g JOSEPH M. MERGEN HOWARD MURPHY SEX BY ATTORN EY.

y 21, 1953 J. M. MERGEN ET AL 2,646,131

PROPELLER PITCH CHANGE MECHANISM s Sheets-Sheet 2 Filed Jan. 29, 1949 INVENTOR. JOSEPH M. MERGEN HOWARD MURPHY BY K ATTORN EY y 1953 J. M. MERGEN ET AL PROPELLER PITCH CHANGE MECHANISM Filed Jan. 29, 1949 INVENTOR.

JCSEPHM. MERGEN HOWARD MURPHY ATTORN EY.

Patented July 21, 1953 1w OFFlCE PROPELLER PITCH CHANGE MECHANISM Joseph M. Mergen, Verona, and Howard Murphy, Glen Ridge, N. J., assignors to- Curtiss-Wright Corporation, a corporation of Delaware Application January 29, 1949, Serial No. 73,586

This invention relates to variable pitch propellers for aircraft wherein power for effecting changes of blade pitch is primarily derived from the rotation of the propeller with respect to a fixed mounting structurel The invention, in part, constitutes improvements on the type of propeller disclosed in copending Chillson application Serial No. 675,383, filed June 8, 1946. While the present invention may be applied to the propeller of said co-pending application, the principles of the invention are also applicable to other types of propellers utilizing hydraulic motors or clutches and brakes for the application of pitch changing power to cyclically operable for the actuation of a power transmission and associated clutches and brakes. Another object of the invention is to provide a power control organization capable'of changing propeller blade pitch in different directions and at variable rates in order that a very fine control of pitch adjustment may be attained in the propeller and also, in order that the pitch adiustment may be accomplished at varying ratesof pitch change and with the greatest speed consistent with pitch change requirements. Another object of the invention is to associate a pulsating propeller pitch changing control arrangement with auxilary propeller and propeller control mechanism to enable the attainment of normal governing operation, reverse pitch, and feathering, and to afford safety featuresin propeller operation which will prevent unwanted kinds of propeller operation under emergency conditions. .A further object of the invention is to provide a pitch changing control construction which may be incorporated into a unitary propeller arrangement, and which will have features of longevity and serviceability which are essential for consistent performance. e

The above and other novel features of the inventi'on will appear more fully in the following detailed description when taken in conjunction with the drawings. The drawings and descriptions 12 Claims. (Cl. 170-46028) 2 however are employed for purposes of illustration of a presently preferred embodiment of the invention and are not to be construed as a definition of the limits of the invention, reference being had to the appended claims to establish the limits of the invention.

In the drawings wherein like reference characters indicate like parts,

Fig. 1 is a schematic view of a propeller system, incorporating a, cycling valve and other features of the invention;

Figs. 2, 3 and 4 are sections respectively on the lines 2, 3 and 4 of Fig. 1;

Fig-5 is an enlarged perspective view of the gear transmission system of a propeller according to Fig. 1; and

Fig. 6 is a view, similar to Fig. 1, showing an alternative arrangement for propeller controls.

Referring first to Figs. 1, 5 and 6, a description will be given of the mechanical and gearing components of a typical propeller with which the invention is adapted to be used. This propeller with its mechanical components is'similar in many respects to that described in the aforesaid co-pending Chillson application Serial No.

675,383, filed June 8,1946. In view of the com-.

plete showing of mechanical details in the aforesaid application, such details are not repeated in the present application; rather, the essential elements have been shown schematically. In the figures, [0 represents a propeller hub which may,

v a worm wheel IB engaged by, a worm l3 driven by a shaft 20 which extends through the rear end of the propeller hub. The shaft 20 carries a pinion 22 drivably engaged with a sleeve gear 2i, mounted upon a sleeve 26 also having a gear 28. The gear 28 comprises a sun gear for a planetary gear set, the latter further comprising a ring gear 30 and spider shafts 32 having pinions 3:3 thereon engaged with and lying between the sun 28 and the ring 30. The-ring 39 as shown is fixed against rotation. The sleeve 26 embraces and is rotatable with and with respect to a propeller shaft 36. Also embracing the propeller shaft and secured thereto is a sleeve 38 including a sun gear 40' and a drive gear-i2. The sun gear 40 engages pinions 44 on the spider shafts 32, the pinions 44 in turn engaging a rotatable ring gear 46. "The gearing vjust described comprises a transfer gear set whereby, by rotatlon or fixation of the ring gear 46, the propeller 3 blades may be caused to change pitch in either direction or to remain in a fixed pitch position.

The gearing elements now to be described comprise means by which the ring gear 46 may be rotated in either direction or locked stationarily. The elements as indicated in Fig. 5 are contained and mounted within a non-rotating housing 48. Driving connections between some of these gears are shown in Figs. 1 and 6 as dotted lines, the gear system in Figs. 1 and 6 being laid out or developed for better comprehension of the functioning of the system. In Fig. 5, the same elements are shown in substantially the configur tion they would occupy in an operative propeller assembly, the various elements being arranged around the propeller shaft 38 for compactness and to minimize weight and space requirements.

The gear 42, rotating with the propeller shaft 36, drives a gear 55 secured to a gear 52. The latter gear engages a gear 54 forming part of a clutch unit 55 which has an output pinion 58 drivably engaged with the control ring gear 46. Another gear 66 is meshed with and driven by the gear 5 3 to drive a clutch unit 62 which has an output pinion 64 drivably engaged with the control ring gear 46. The clutch units 56 and 62 comprise hydraulically actuated multi-disk driving connections which may selectively be engaged by the application of hydraulic pressure to conduits 86 and 68'respectively during normal propell'er operation. When hydraulic pressure is admitted to the unit 56, the gears 54 and 53 will be locked together for unitary rotation, the arrangement being such that engagement of the clutch 55 will move the control ring gear 46 to produce pitch increasing movement of thepropeller blades. Since the gear 50 rotates oppositely from the gear 54, engagement of the clutch 62 will produce opposite rotation of the control gear 46 and will produce pitch decreasing motion of the propeller blades '14. When neither clutch 56 or 62 is engaged, "the pinions 58 or 64 are free, althoughthe gears 54 and G!) will be driven continuously due to rotation of the gear 42.

A brake unit T0 is provided in the housing 48 having a pinion l2 engaged with the control drive gear 46. When the brake is engaged, theg-ear l2 and. consequently the control gear 46 are lo cked against rotation, thereby preventing propeller blade pitch change. 'Thebrake l'll is of the same type as is shown in'l ig. 13 of the aforesaid Chillson application Serial No'. 675,383, thebrake including a centrifugally responsive mechanism whereby failure of oil pressure in the system will cause locking of the brake and prevention of further pitch change even though the control system may call for pitch change. In this connection, the brake assembly 70 carries a gear 14 driven from'the drive gear 42 which operates the centrifugal device. The brake I0 is provided with a hydraulic conduit 76 connected to the source of hydraulic pressure providing .pressure fluid to operate in conjunction with the centrifugal device. Another conduit'lB is connected to the selective valvemechanism to bedescribed which controls normal engagement or disengagement of the brake mechanism. 7

The propeller system further includes an independent motor86 selectively operable at times to actuate the propeller pitch changing -mechanism when hydraulic power; is not available.

This motor is connected through-gears 8l, 82, 3 and '84 to a driving pin 85 engageable at times with a connection 86 drivably connected to the CAD gear 12. Upon operation of the motor 80, the driving connection is established between and 86 whereby the pitch control gear 46 may be rotated in either direction to accomplish pitch change without recourse to the hydraulically operated clutches and brakes 56, 62 and I0. These mechanisms just described are disclosed in detail in the aforesaid Chillson .patent application and it is deemed unnecessary to describe their detailed operation in the present application.

Although the transfer gearing is disclosed in the aforesaid Chillson application, a brief review of its mode of operation is here presented. The ratios of the 'two planetaries 46, 44, 40, and 30, 34, 28, are identical. Under fixed pitch conditions, the blade control gear 46 is stationary and the sun gear 40 rotates with the propeller. Thus, the spider shafts 32 will rotate at an intermediate propeller speed. Since the ring gear 30 in the front planetary is stationary, the sun gear 28 on the sleeve 26 will be caused to rotate at propeller speed. Thereupon, the gear 24 will rotate with but not relative to the propeller and. no pitch change will occur. If, however, the control gear 46 is rotated either in the direction of or opposite to the direction of propeller rotation, the sleeve gear 2 8 will be caused to rotate in the appropriate direction relative to the propeller shaft, while also rotating therewith. Thus, rotation will be imparted to the gears 24 and 2-2 to attain pitch changing movement of the blades 54.

The mechanism described above, under the influence of suitable control devices, allows of looking of propeller blades against pitch change by engagement of the brake Hi and allows of increasing or decreasing pitch-changeat a constant rate by solid engagement of either of the clutches 5B or 82. The system also provides for emergency propeller pitch change by the'use of the feathering motor 86.

The control mechanism now to be described includes a cycling valve along with hydraulic supply and control arrangements by which the clutches 55 and 62 and the brake -19 may be actuated on a pulsating basis, the pulsations being applied at substantially constant frequency but at varying dwell to give the effect of a variable rate of pitch change. Under conditions of normal governing operation of a propeller, a low rate of pitch change is desirable. When a demand'is made for pitch reversal or for feathering, a high rate of pitch change is desirable. If propeller pitch change of considerable magnitude is desired during normal operation it is beneficial to provide an initial high rate of pitch change, which gradually diminishes toa low rate as the desired pitch angle is approached. The ability to secure a variable rate of pitch change is particularly desirable in connection with the application of controllable pitch propellers to internal combustion turbines where the propeller control coordinates with the controls for the turbine to produce speed and power-control for the turbine.

In the system of Fig. 1, the propeller is adapted for rate of pitch change control whilein Fig. 6 the system is adapted for blade angle control. The differences will be described later but the essential parts of the control system-are similar for both arrangements.

Referring now to Figs. 1 through'4,'a hydraulic system for actuating the clutches 55 and-fi2 and the brake it} includes a reservoir 19E feeding a pump I02 whose output line is indicated at I04. Hydraulic lines are indicated in dot-dash lines to distinguishthem from dotted line mechanical auxiliaries and particularly to a cycling valve assembly I88 through a passage I III. The cycling valve comprises two bores I I2 and I I4, communicating with one another at their upper ends as at H6, both bores being fitted with piston-equipped valve stems II8 and I20 respectively. The valve stems H8 and I26 are pressed downwardly bysp-rings I22 and I24, the valve, stems extending downwardly through the valve housing M8 to engage an axially movable cycling cam' I26 carried on a shaft I28. The cycling cam shaft is driven, as noted by the dotted line IJB,.from"the propeller gear 42 whereby the cam rotates at a speed corresponding to propeller speed. The cam I26, when disposed as shown, provides for the dropping and lifting of the valve stems H8 and I28, the dropping of the stems occurring at points I 39 on the cam, the stems being raised as the cam rotates by the cam riser I32. cam I28 are relieved in helical form. If the cam shaft I28 is moved axially'to the left the cam riser I32 will lift the stem I20 and the stem will drop off the cam late or early in accordance with the axial position of the cam, atpoints such as I38 or I38" shown in Figs. 3 and 4. Correspondingly, if the cam be moved bodily to the right, the valve stem I I8 will rise at the same instant during each turn of the cam but will descend in accordance with the extent of movement of the cam toward the right. During such movements, the dwell of the valve stem in the raised position will vary in accordance with the axial position of the cam I but the frequency-of reciprocation of the valve stem remains the same.

The cam shaft I28 is connected to a rate of pitch change control lever or member I34 througha suitable linkage such as the arm I36 and the yoke connection IBIi-MU, the element I38 comprising a yoke and the elements I40 comprising lands on the shaft I28 between which the yoke- I38 is engaged. Operation of the lever I34 in a clockwise direction is arranged to yield as shown increasing propeller blade pitch while counterclockwise operation of the lever I34 is arranged to yield decreasing propeller pitch. 7 When the cam I25 is centered as shown, both valve stems I I8 and I20 are held in a raised position by means to be described. Leftward cam movement releases stem I28 for reciprocation and rightward cam movement releases stem H8 forreciprocation. Pressure fluid from the header I 84 enters the valve bore I I4 through theline I I8. With leftward cam movement the valve stem I25 descends upon rotation of the cam I26, aivalve piston I4I descends and the line IIII communicates with a line Hi2, transmitting pressure fluid to the conduit of the increased pitch clutch 53 thereby engaging said clutch and effecting a drive from the propeller gear 2 to the pitch control gear 46. Concurrently, a valve head I 44 on the stem I26 lowers and connects a passage I46 Within the valve I88 to the cross-connection IIB between the valve bores which is vented to the sump see through passages I 48 and I48. Since the energizing conduit $8 for the brake "I8 is connected as at I 58 to the valve housing I08, and since the valve stem I I8 is held in a raised position, the brake It is now ventedto the sump, disengaging the brakeand permitting the indicated The ends of the 1 cycles when there is no call therefor.

creased pitch change'is called for, the valve stemi increased pitch operation of the propeller to takeplace. As the cam I26 continues to rotate, the valve stem I20 is raised, establishing engagement of the brake 18 through the conduits H8, I46 and IE9, and the clutch 58 is de-energized through drainage thereof through the conduits 66, I42 and I 38.

If the cam I26 is moved rightwardly by the control I84 for pitch decrease the valve I I 8 reciprocates as the cam rotates. Withthe stem II8 raised, the decrease pitch clutch 62 is disengaged, the clutch cell being drained through the conduit E58, a conduit I52 entering the valve housing I88 below the lower piston I53 on the valve stem I I8 and thence to the sump through the passages I '48 and I48. Concurrently, the brake is energized by pressure fluid passing thereto through the passages III I46, I58 and 18. When the stem II8 and'its piston I53 are in the lower position due to rotation of the cam I28, pressure fluid will flow to the decreased pitch clutch 68 through the passages IIG, I48 and I52. 1% the same time the upper piston I55 on stem I58 descends, and the brake 18 will be disengaged by the relief of fluid therein through the passages 18, I59, II 6, I48

and I48. 7

In the above description it was assumed tha when the cam I25 centered, both valve stems H8 and IZEI will be held in the uppermost position. This is accomplished by brake shoes I56 and I58 embracing the respective valve stems, said brake shoes being held in engagement with their stems by small brake cylinders Ice and I62 connected hydraulically to a valve unit I64 operated through a link I66 by the rate of pitch change control lever I34. The valve unit I8 5 is connected at I68 to the pressure feedline I 84 and is connected at Ill and, I72 to the drain line I43. When no pitch change is called for, pressure fluid passes to both brake cylinders Hill and IE2: through the valve I54, locking both valve stems H8 and I28 in the raised position so that, as the cam I26 rotates, the valve stems do not drop into the recesses on the cam I26, thus avoid.- ing undue wear on the valve mechanism during propeller operation and prevening pitch changing v /honin- Ilaii is moved to the right thereby connecting the brake cylinder I62 to the drain I48 throughthe valve I64, and leaving'pressure on the brake cylinder I60. I reciprocate as the cam I26 rotates. If acall for pitch decrease is made by the lever I 34, the brake cylinder Ifillisconnected to the drain I48, leaving pressure on the brake cylinder I62. .This. holds the valve stem I28 in the raised position but allows the valve stem IE8 to reciprocate as the cam I26 rotates.

When either a call for increased pitch or decreased pitch is made by movement of the lever I34 and by axial movement of the cam I26, the appropriate valve stem H8 or I28 will reciprocate and the active valve will alternately cause en- ,gagement and disengagement of the clutch 5B or 82 with concurrent respective disengagement and engagement of the brake Ill. If the control lever I34 calls for a high rate of pitch change, the cam I26 is shifted a considerable distance axially; for instance, the cam section at the section line 4 may lie beneath the valve stem I20 and as the cam rotates there will be a comparatively brief period during one turn of the cam when the clutch 56,15 disengaged and a comparatively long period during the rotation of the cam when the; clutch 56 is This permits the valve stem IZIB to engaged. Thereby, nearly full rate of pitch change is attained. For any intermediate axial position of the cam I26 a lesser period of clutch engagement is afforded and a longer period of clutch disengagement, giving a lesser rate of pitch change. When the cam is centered as shown, the valve stems II8 and I20 are held in the raised position so that no pitchchange may occur since neither of the clutches 56 or 62 are given an 'opportunity to engage.

To review briefly the-operation of the valve unit I08, either but not both of the valve stems II8 and I20may reciprocate at one time, When the valve stem H8 reciprocates, its upper piston 555 alternately lies above and below the brake conduit I50, Likewise the lower .piston I53 alternately vents the decreased pitch clutch 62 or permits pressure fluid to be imposed there-on from the conduit I45 and the supply line Hi]. When the valve I-2fl is active, the upper piston Isa alternately opens the line I46 to the pressure source or opens it to the drain cavity H6, said passage I46 being connected to the brake. Concurrently, the lower piston I4I alternately connects the increased pitch clutch 56 to the drain or connects the clutch to the pressure source through the conduit I I0.

Provision is made in the valve assembly 63 to hold both of the valve stems I I8 and E29 in an upward position in case of failure of the hydraulic fluid pressure supply. For this purpose, a cavity I82 is provided in the valve bore H2 and a cavity I84is provided in the valve bore I I4, both of these cavities being isolated from the previously described active portions of the valve bores by a partition I88. Both of these cavities are connected through conduits I88 and I90 respectively to a valve unit I92 supplied with pressure fluid from the fluid pressure supply line I04 through a conduit I94. Within the cavities I82 and I84 are pistons I95 and I98 respectively spring pressed upwardly by springs 20!] and 202. When oil pressure supply is normal, the pistons I96 and I98 are pressed downwardly, compressing the springs 200 and 292. Should oil pressure relax in either cavity, the pistons I96 and I98 rise within the cavities and engage stops 204 and 208 respectively secured to the valve stems H8 and I20. The springs 200 and 202 are stronger than the springs I22 and I24 at the top portions of the valve bores and thus, may overcome the upper springs and force the valve stems I it and I20 upwardly, thereby holding the increase and decrease pitch clutchesB'e and 62 disengaged and leaving the brake 70 engaged if there is any residual pressure in the hydraulic pressure system. Whether or not pressure exists at this time in the brake "I is immaterial for the centrifugal device in the brake I0, referred to in the aforesaid application, will lock the propeller in a fixed pitch position if the propeller be rotating. If the propeller is not rotating, selective control of pitch will be afforded by the feathering motor 80-.

Operation of the feathering motor 80 is responsive'both to operation of the control lever I34 :and to lack of adequate oil pressure from the pump I02 to operate the propeller hydraulically. To this end, the lever I34 operates a pair of switches 2I0 and 2I2 for the selection of either increase or decrease pitch change. Both of these switches are serially connected with the switch 2 I' l which is normally open when oil pressure exists, through a hydraulic cell 216 connected to the pressure conduit I04. The switch 2I4 is connected to a power source such as a battery 2I8 and thence 8 to ground. Should oil pressure fail, switch 2I4 closes under the influence of a spring 220 and increase -or decrease pitch is attained through closure of the switches 210 or 2.I 2 by the lever I3'4. Closure of these switches respectively energizes conductors 222 or 224 leading through limit switches'226 and 228 to theincrease and decrease field windings within the motor 80. Said motor, like that-disclosed in the aforesaid co-pending application, comprises a brake which is released by the energization of the .increaseor decrease pitch fieldwindings of the motor, thus permitting the motor ipinion BI to turn and to rotate the pitch control .gear 46 of the propeller to cause pitch change in a manner previously described.

Provision is made for establishing pitch limits beyondwhich the blades of the propeller may not be rotated. A screwshaft 230 carries amnion-232 driven from the pitch control gear 45 as shown. Upon the screw shaft 230 is asleeve 234 having end flanges 236 and .238. The position of the sleeve 234 on the screw 23!! is established by the instant pitch position of the propeller "blades since, for any pitch position'ofathe propeller-blades there will be a definite position'of the pitch control gear 46 which drives the screw shaft 2%. When the propeller blade tpitch becomes high, the sleeve 234 will move to the left as shown and when the limit is reached, the flange 230 on the sleeve will open switch 226 and also will move the core 2% of the valve I92 to the left. By opening the switch 2-26, pitch increasing operationof the electric motor will be stopped if the latter is operating. By moving the valve core of the valve 240 to the left,'if the hydraulic system is operating, pressure fluid will be cut ofif from the passage I00 leading to the cavity I84 cooperating with the increase pitch valve stem I20. With this action, the'spring 202 in the valve bore I I4 will hold the valve stem I20 in the raised :position stopping such pitch increasing movement as may be atforded by the hydraulic system.

If thepropeller-bladesmove to the low limiting pitch, the sleeve 234 on the screw shaft 230 will move toward the right whereupon the sleeve flange 236 will open the :limit switch 220, cutting off ,power to the electric motor and stopping decreasing pitch-change of the hladesif the electric motor 801s active. If the hydraulic system is active, movement of'the valve core 240 to the right, by the sleeve flange 36, will cut off the flow-of pressure fluid to the conduit I38 and the cavity 1-8-2 associated with the :decreasing pitch valve stem 1 It. Thereupon, the decreasing pitch valve stem -II8 will rise under the influence oi the-spr1ng200, stoppingoperation of the decreasing pltCh'ChltCh 62 if the latter had been operatmg under the influence of hydraulic pressure.

In the above description reference has been madeto Fig. 1 wherein the lever I34 is a control for the rate of pitch change. 'In this embodiment, the screw shaft 236 and its associated translatable sleeve 234 provides a takeoff for a pitch indicator which may, if desired, be utilized in conjunction with a coordinated propeller "and gas turbine control system.

Now referring to Fig. 6, substantially the same mechanism is shown as above described with the exception that a control lever 250 is provided which isselectively movable to any one of a number of positions 'to establisha certain blade angle setting. Ihis lever 250 is equipped with a sector gear 252 engaged with a translatable rack 254 having a lever 256 pivoted thereto. Said lever is provided with two additional spaced apart pivots 258 and 26m The pivot 258 connects by a link 262 to the pitch indicating sleeve 23% whereby the position of the pivot 258 is fixed by the in stant pitch setting of the propeller blades. The pivOtZfifl connects through a link 264, another link 2% centrally pivoted at 263 to a fixed member, and thence to a yoke 2T0 engaging the lands I40 on the cam shaft 128. When a call for an increased blade pitch setting is made, as by rotat- 'ing the sector 252 in a counterclockwise direction, the link 256 swings clockwise about the instantaneously fixed pivot 258, activating the valve assembly [68 to call' for increased pitch under the influence of the hydraulic system or alternatively calling for increased pitch through the switch 210 if the electrical system: is active. As pitch increase occurs, the sleeve 234 will move leftwardly along the screw shaft 23d, pulling the pivot 258 and swinging the link 2% oounterclockwise about the rack pivot until the call for increased pitch has been cancelled by attainment of the increased pitch called for by blades will "be established should the hydraulic system fail when the propeller is rotating.

The control system of this invention, as inferred in the introduction to the specification, enables varying rates of pitch change to be attained in a hydro-mechanical system and further provides for emergency pitch change in a mechanical type propeller in case of i ailure or inoperativeness of an associated hydraulic systern.

The showings of Figs. 1 and 6 are primarily schematic in character and while they include all of the essential electrical and mechanical components are not presented as a final mechanical design. The several hydraulic, mechanical and electrical elements involved in themselves are familiar to those skilled in the art and these units may be coordinated in the aggregate propeller design to attain desired characteristics of compactness, simplicity and light weight. Re-

ferring briefly to Fig. 5, the entire cycling valve mechanism may be contained within a .c'ornpara tively small housing tilt" driven. from the power gear 42. Other hydraulic and electrical elements of the system may be combined in additional housings secured within the fixed propeller structure 68, such elements including the pressure switch 2M and other semi-independent assemblies. V 1 Though several embodiments illustrating the invention have been shown and described, it is to be understood that the invention may be applied in other and various forms. Changes may be made in the arrangements, withou't'da parting fromthe spirit of the invention. Ref- 'erence should be had to the appended claims for definitions of the limits of the invention.

What is claimed is: I is In a propeller comprisinga hub and blade adjustably mounted therein for pitch change, mechanism including a gear train and a clutch 10 therein 'drivably connected to the blade for changing blade pitch, said clutch being engageable to cause pitch change and disengageable to stop pitch change, cycling means connected to control clutch operation, and connected to and driven by said propeller to cause repeated clutch engagements and disengagements at predetermined frequency means included in said cycling means to vary dwell of clutch engagement and disengagement in each cycle accordingly as the blades are close to or far from the desired blade pitch, and a brake secured to the propeller engageable to lock said blade against pitch change and to unlock said blade for pitch change, said brake being operated by and connected to said cycling means to engage as said clutch is disengaged, and vice versa. 1

2. In a propellercomprising a hub and blade bein 'hydraulically operated, said cycling means comprising a hydraulic valve connected to said clutch and arotatable and slidable cam operable to open and close said valve, and means to slide said cam to control operation of said cycling means.

3. In a propeller comprising a hub and blade adjustably mounted therein'for pitch change, mechanism including a gear train and a clutch therein for changing blade pitch, said clutch being engageable to cause pitch change and disengageable to stop pitch change, cycling means controlling clutch operation, driven by said propeller, to cause repeated clutch engagements and disengagements at substantially constant irequency and at varying time periods for each cycle, means to initiate and stop operation of said cycling means in relation'to said clutch, said clutch being hydraulically operated, said cycling means comprising a hydraulic valve con nected to said clutch, and said cycling means including also a slidable rotatable cam having a lobe of varying width along its length operable to open and close said valve, the axial position of said cam establishing the open and close dwell of said valve and consequently, the driving and non-driving dwell of said clutch.

4. In a propeller comprising a hub and blade adjustably mounted therein for pitch change, mechanism including a gear train and a clutch therein for changing blade pitch, said clutch being engageable to cause pitch change and disengageable to stop pitch change, cycling means controlling clutch operation, driven by said-propeller to cause repeated clutch engagements and disengagements at predetermined frequency means included in said cycling means to vary dwell of clutch engagement and disengagement in each cycle accordingly as the blades are close to or far from the desired blade pitch, said clutch being hydraulically operated, and said cycling aneans comprising a hydraulic valve connected movable relative to the valve and having a valve opening lobe varying in circumferential length along the cam, whereby dwell of valve opening, is determined by the axial position of said cam. lobe relative to said valve, and means to move said cam axially to control operation of said cycling means.

5. In a propeller comprising a hub. and blade adiustably mounted therein for pitch change, mechanism including a gear train and a clutch therein drivably connected to the blade for changing blade pitch, said clutch being engageable to cause pitch change and disengageable to stop pitch change, cycling means connected to control clutch operation, connected to and driven by said propeller to cause, repeated clutch engagements and disengagements at predetermined irequency means includedv in said cycling means to vary dwell of clutch engagement and disengagement in each cycle accordingly as the blades are close to or far from the desired blade pitch, means connected to said cycling means to control operation thereof a brake secured to the propeller engageable to lock said blade against pitch change and to unlock said blade for pitch change, said brake being operated by and connected to said cycling means to engage as said clutch is disengaged, and vice versa, said brake and clutch being hydraulically operated; said cycling means comprising a valve connected to operate said brake and clutch coincidentally and in opposition, and a rotatable cam engageable with said valve for actuating same.

6. In a propeller comprising a hub and blade adjustably mounted therein for pitch change, mechanism including a gear train and a clutch therein drivably connected to the blade for changing blade pitch, said clutch being engageable to cause pitch change and disengageable to stop pitch change, cycling means connected to control clutch operation, connected to and driven by said propeller to cause repeated clutch engagements and disengagements at, predetermined frequency means included in said cycling means to vary dwell. of clutch engagement and disengagement in each cycle accordingly as the blades are close to or far from the desired blade pitch, a, brake secured to the propeller engageable to lock said blade against pitch change and to unlock said bladefor pitch change, said brake being operated by and connected to said cycling means to engage as said clutch is disengaged, and vice versa, saidbrake. and. clutch being hydraulically operated; said. cycling means comp-rising a valve connected. to. operate. said brake and clutch coincidentally and in opposition, and a rotatable cam drivably connected to the propeller and engageable with said valve; for actuating same, said cam being axially movable and having a valve-lifting and engaging lobe of varying circumferential length axially therealong; and means connected to the cam to move said cam axially to vary the dwell of clutch and brake operation for each cycle ofoperation thereof.

7. In a propeller comprising a hub and blades adjustably mounted therein for pitch change, continuously rotating power means for changing blade pitch, mechanism connecting said means with said blade including a pitch increasing hydraulically operated clutch and a pitch decreasing hydraulically operated clutch; a valve connecting a hydraulic supply to each clutch, continuously rotating means comprising a cam for operating said clutch valves intermittently, and selectively operable means to operatively connect 12 said cam and one said clutch valve to cause intermittent operation of the associated clutch.

8. In a propeller comprising a hub and blades adjustably mounted therein for pitch change, continuously rotating power means for changing blade pitch, mechanism connecting said means with said blade including a pitch increasing clutch and a pitch decreasing clutch, continuously rotating means comprising a cam for operating said clutches intermittently, selectively operable means to operatively connect said cam and one said clutch to cause intermittent operation thereof, a brake to anchor said blades against pitch change, and means to release said brake, operated by said cam, simultaneously with the engagement of either clutch.

9. In a propeller comprising a hub and blades adjustably mounted therein for pitch change, a power takeoff on the shaft of th p p r, gearing connecting said takeoff with the propeller blades for pitch change thereof, hydraulically operated clutches in said gear train connected to transmit pitch increasing and pitch decreasing motion from said takeoff to said blades, either clutch when solidly engaged affording a high rate of blade pitch change; and means to reduce and vary the rate of pitch change comprising hydraulic valves, one connected-to control operation of each said clutch, and means driven by the propeller and selectively operable, connectable to engage and open and close either of said valves intermittently at predetermined frequency substantially proportional to propeller speed and for varying periods of open dwell according to the selected operation.

10. In a propeller comprising a hub and blades adjustably mounted therein for pitch change, a power takeoff on the shaft of the propeller, gearing connecting said takeoff with the propeller blades for pitch change thereof, hydraulically operated clutches in said gear train connected to transmit pitch increasing and pitch decreasing motion from said takeoff to said blades, either clutch when solidly engaged aliording a high rate of blade pitch change; and means to reduce and vary the rate of pitch change comprising hydraulic valves, one connected to control operation of each said clutch, and means driven by the propeller and selectively operable, connectable to engage and open and close either of said valves intermittently at predetermined frequency substantially proportional to propeller speed and for varying periods of open dwell according to the selected operation, said propeller including a hydraulically operated brake connected within said gear train to prevent pitch change of said blades, and said hydraulic valves having means therein respectively to control fluid feed to engage and disengage said brake coincidentally with disengagement and engagement of said clutches.

11. In a propeller pitch changing mechanism, gearing to rotate the propeller blades in their sockets including a drive gear, a power gear means to drive said power gear, a clutch engageable to interconnect said drive and power gears, a device movable to engage and disengage said clutch, a rotating cam engageable intermittently with said device for alternately engaging and disengaging said clutch in successive cycles of predetermined frequency, and a member connected to said cam and moving it relative to said device for varying the time interval of clutch engagement during each said cycle.

12. In a propeller pitch changing mechanism,

13 gearing for rotating the propeller blades in their sockets including a drive gear, a power gear, means connected to drive said power gear, a clutch engageable to interconnect said drive and power gears, a, device connected and movable to engage and disengage said clutch, a movable and rotating cam engageableintermittently with said device for alternately engaging and disengaging said clutch in successive cycles of varying dwell and predetermined frequency means connected to drive said cam at substantially constant speed, and means connected to said cam for moving said cam relatively to said device independently of rotary movement of thefcam to vary the time interval of clutch engagement during each said cycle.

JOSEPH .M. MERGEN. HOWARD MURPHY.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Caldwell et a1. Jan. 7, 1936 Setterblade July 8, 1941 Thomas et a1 Nov. 23, 1943 Forsyth Mar. 2, 1948 Doussain Nov. 30, 1948 FOREIGN PATENTS 7 Country Date Great Britain July 31, 1941 Great Britain Oct. 9, 1946 Great Britain Oct. 9, 1946 

